Cindy Eckley’s recovery blipped this spring when she learned the man accused of hurling a 40-pound sandbag at her from an Interstate 96 overpass was pursuing an insanity defense. The latest in the prosecution of David Vincent-Charles Garcia seemed more than vexing to the Plymouth business owner. Her vision was permanently damaged by the glass that pierced her left eye once a 40-pound load of construction materials shattered her windshield six months ago. “He has a long criminal history,” said Eckley, rejecting Garcia’s claims of mental illness. “He has a long record. Not once on any of his other charges has this been brought up. It’s just a stall tactic.